单项选择题 Restrictions occurring in the small orifices of pneumatic control system components can be used by （）

单项选择题 In a pneumatic automation system, a unit producing a signal to govern the position of the controller of the measured variable, relative to the value of the measured variable, is said to have（）.

单项选择题 In an automation system, the effect of a control action sensed by a controller is known as （）